1. Field of the Invention
The present invention relates to magnetic heads and more particularly to digital recording magnetic heads for use on digital video tape recorders and the like.
2. Description of the Prior Art
A digital recording/reproducing apparatus, which converts video signals into corresponding digital signals, records the digital signals on a magnetic tape and reproduces the digital signals recorded on a magnetic tape, is known. In general, an apparatus of this type distributes digital signals into a plurality of channels, and records or reproduces the digital signals of the respective channels by individual magnetic heads. Such a digital recording/reproducing apparatus uses, for example, two magnetic heads mounted on a rotary drum in diametrically opposite positions for recording and reproducing. In recording signals by such a digital recording/reproducing apparatus, it may occur that signals recorded by the preceding magnetic head are erased by the succeeding magnetic head due to the eccentric rotation of the rotary drum. Accordingly, the ratio of erased signals to remaining signals increases, so that the reproducing output of the digital recording/reproducing apparatus is not sufficiently high and the bit error rate is greatly increased.
To solve such problems, a recording/reproducing method uses simultaneously two magnetic heads combined in an integral magnetic head unit and disposed respectively at different azimuth angles on a rotary drum for recording/reproducing operations. FIG. 34 shows a recording format for recording signals on a magnetic tape 501 by such magnetic heads combined in an integral unit. The signal is recorded at a fixed position on each track on the magnetic tape 501 to extend the recording time of the magnetic tape 501. Accordingly, a signal to be recorded by the succeeding magnetic head 503 is supplied to the succeeding magnetic head 503 with a delay relative to a signal to be recorded by the preceding magnetic head 502, which delay corresponds to a distance obtained by subtracting a step between tracks from the gap distance GL.
When this digital recording/reproducing apparatus is used as a video tape recorder (VTR), a video signal and an audio signal are recorded in separate recording regions. In recording a video signal and an audio signal in such a mode, the video signal and the audio signal must be recorded separately by a so-called after-recording method in which the audio signal is recorded after the video signal.
Because of crosstalk, it is difficult to use only one of the two magnetic heads 502 and 503 combined in an integral magnetic head unit. If an audio signal is recorded in an after-recording mode to obviate crosstalk, the succeeding magnetic head 503 remains in a video signal recording region as indicated by a broken line (FIG. 34) when the preceding magnetic head 502 is at the front end of an audio signal recording region to start recording the audio signal. Therefore, if the preceding magnetic head 502 starts recording the audio signal at this time, some recording signal flows through the succeeding magnetic head 503, which may adversely affect the video signal. Thus, after-recording is virtually impossible. When the two magnetic heads 502 and 503 are combined in an integral magnetic head unit for simultaneous recording and reproducing to record signals on and to reproduce signals from a magnetic tape, a positional relation between the two magnetic heads 502 and 503 is very important.